CN109001034A - A kind of test method damped after Damage for Brittle Material - Google Patents
A kind of test method damped after Damage for Brittle Material Download PDFInfo
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- CN109001034A CN109001034A CN201810908887.2A CN201810908887A CN109001034A CN 109001034 A CN109001034 A CN 109001034A CN 201810908887 A CN201810908887 A CN 201810908887A CN 109001034 A CN109001034 A CN 109001034A
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- concrete sample
- concrete
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- brittle material
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
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- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
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- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
A kind of test method damped after Damage for Brittle Material, comprising the following steps: casting concrete test specimen, standard curing 28 days；The bottom of concrete sample obtained is vertically fixed in test device, installation protects cabinet and applies xial feed on concrete sample；Protection cabinet is unloaded, applies exciting force in the upper end of concrete sample and the acceleration transducer by being arranged on concrete sample records acceleration signal, test analysis is carried out to the power performance of concrete sample, calculates damping ratio.The present invention can be further applied load simultaneously when testing damping, concrete material damping capacity after different concrete materials and damage is tested, test result is accurately credible, it can be used for the damping characteristic of the different military service stage concrete materials of comparison, the present invention has significant engineering value and scientific value.
Description
Technical field
The invention belongs to technical field of buildings, and in particular to the test method damped after a kind of Damage for Brittle Material.
Background technique
Structural damping is made of a variety of different damper mechanisms, mainly includes material damping mechanism and interfacial damping mechanism.
Material damping refers to the characteristic of material mechanical vibrational energy due to caused by internal cause consumption, and also known as in-fighting is to measure material
The important indicator of the new energy of damping itself.Can various responses be all the functions of damping in structural analysis, therefore correct Damping Estimation
The reliability of dynamic structural analysis result is directly influenced, therefore in Dynamical Analysis for Building Structure, the selection of damping ratio and taken
It is worth particularly significant.
In the modal idenlification of structure, the accuracy of identification of damping ratio is far below the accuracy of identification of eigenfrequncies and vibration models, test
As a result by more bad when noise jamming, while damping measurement is less reproducible, small resistance especially this to concrete material
Damping system.But one reference value only is given according to structure type to damping ratio in code for structural design, without considering
Difference caused by the selection of material is different in practical structures.Therefore it in order to design the structure with more preferable anti-seismic performance, necessarily needs
Concrete structure damping capacity is being studied from material level.
Common concrete test method has the arrangement of steel wires in concrete to be fabricated to beams of concrete progress damping test
Method and production plain concrete test damping by the way of suspension.It can produce 1mm's long after being implanted into steel wire in concrete
Beam tests damping using the method for freely-supported or cantilever, and it is preferable to measure vibratory concrete signal in this way, but due to being configured with steel
Silk, therefore cannot really reflect the damping property of concrete.Another method makes the plain concrete that depth-width ratio is 1:4 or so
Section is tested with hang and is damped, and the damping of concrete itself can be directly acquired, but since the beam of production is shorter, is surveyed
Signal contain more noise, and vibration frequency is higher reduces damping test precision.
For the research of damping, can be used in the judgement to material damage, thus for Damage for Brittle Material after
Damping capacity test is of great significance between the military service period and performance for studying concrete.But concrete is with larger
Brittleness, this makes concrete be not suitable for being moved again after infliction of a lesion.And due to the brittleness of concrete, commonly for beam
The mode of the application amount of deflection of body, which applies damage, cannot be such that damage is uniformly distributed in the material, thus be also not suitable for coagulation great soil group material
Material.
Summary of the invention
The test that the purpose of the present invention is to solve the above-mentioned problems and damps after providing a kind of Damage for Brittle Material
Method can accurately measure the damping property under the damage of concrete material difference.
The purpose of the present invention is achieved through the following technical solutions:
A kind of test method damped after Damage for Brittle Material, comprising the following steps:
(1) casting concrete test specimen, standard curing 28 days；
(2) bottom of concrete sample obtained is vertically fixed in test device, installs and protects on concrete sample
Protecting box body simultaneously applies xial feed；
(3) protection cabinet is unloaded, applies exciting force in the upper end of concrete sample and by being arranged on concrete sample
Acceleration transducer record acceleration signal, test analysis is carried out to the power performance of concrete sample, calculates damping ratio.
Further, the concrete sample is cuboid, having a size of 100mm × 150mm × 1300mm.
Further, the test device is universal testing machine, and the lower part of the universal testing machine is equipped with solid for clamping
Determine the stationary fixture of concrete sample.
Further, the clamping length of the concrete sample bottom is 200mm.
Further, the upper end of the concrete sample applies exciting force, and exciting force applying mode is tapped using power hammer, struck
Number is hit not less than 6 times.
Further, the load(ing) point of the upper end exciting force of the concrete sample on concrete sample long side center line away from
At the position 50mm of end.
Further, the opposite face of concrete sample exciting force acting surface is arranged in the acceleration transducer, is located at mixed
On solidifying soil test specimen long side center line at the position 150mm of its end.The acceleration transducer selects piezoelectric type acceleration to pass
Sensor.Transducer range is not less than 5 times of 1 rank frequency of concrete material, and is not more than 20 times of 1 rank frequency of concrete material.
Further, the size of the protection cabinet is 100mm × 150mm × 1000mm, by two L-type component combinations
At.
Further, the damping ratio of concrete sample, which calculates, uses following formula:
E=1200 ρ f0i/Ci 2 (1)
η=Δ f0i/f0i (2)
In formula: ρ --- the line density of concrete sample, kg/m3；
Δf0i--- the half-power bandwidth of concrete sample the i-th rank mode, Hz；
I --- resonance order: 1,2,3 ... ...；
Ci--- the i-th rank mode shape coefficients；
The elasticity modulus of E --- concrete sample；
η --- damping ratio.
Further, the measurement accuracy of concrete material density is not less than 3%, and the worst error of concrete material size is not
Greater than 2%.
Compared with prior art, the invention has the following advantages that
1, measuring accuracy is high: due to being tested using cantilever beam, test signal have lower frequency and it is stronger plus
Speed signal.
2, convenient test: only needing to install simple fixture on universal testing machine can be tested, and can be added in test specimen
Damping test is carried out after load in situ.
3, analog difference military service situation: realize that simulation regeneration concrete exists by being axially further applied load in concrete sample
Degree of impairment under the difference military service period.
Detailed description of the invention
Fig. 1 is the test flow chart of the method for the present invention；
Fig. 2 is the schematic diagram of the used test device of this test method.
Specific embodiment
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.
As shown in Figure 1, after a kind of Damage for Brittle Material damping capacity test method the following steps are included:
Step 1: determining testing program.
Example carries out the regeneration concrete production of different recycled aggregate incorporation efficiencies and the ratio of mud.Test is strong using novel concrete
It spends the concrete that grade is C30 and mixes recycled aggregate, to measure the damping of the regeneration concrete under different recycled aggregate Replacement rates
Changing rule, recycled aggregate incorporation efficiency take 0,50% and 100% respectively.
Step 2: casting concrete test specimen, using standard curing by 28 days.
Step 3: carrying out test analysis to the power performance of test specimen, including damping test and xial feed apply and unloading
Damping test after damage afterwards.
Fig. 2 is used test device by this test method, and test device is universal testing machine, and the lower part of universal testing machine is set
There is the stationary fixture for gripping concrete sample, the clamping length of concrete sample bottom is 200mm, concrete sample
Upper end apply exciting force, exciting force applying mode using power hammer tap, number of taps be not less than 6 times, concrete sample it is upper
Hold the load(ing) point of exciting force on concrete sample long side center line at the position 50mm of end, acceleration transducer setting exists
The opposite face of concrete sample exciting force acting surface is located on concrete sample long side center line apart from its end position 150mm
Place, protecting the size of cabinet is 100mm × 150mm × 1000mm, is formed by two L-type component combinations.
It is specifically tested using the present apparatus:
Comparative example 1, the incorporation efficiency of recycled aggregate are 0, the test damping when not adding xial feed.
Comparative example 2, the incorporation efficiency of recycled aggregate are 50%, the test damping when not adding xial feed.
Comparative example 3, the incorporation efficiency of recycled aggregate are 100%, the test damping when not adding xial feed.
Embodiment 1 after applying 30% peak load, tests the damping under faulted condition using the test specimen of comparative example 1.
Embodiment 2 after applying 70% peak load, tests the damping under faulted condition using the test specimen of comparative example 1.
Embodiment 3 after applying 30% peak load, tests the damping under faulted condition using the test specimen of comparative example 2.
Embodiment 4 after applying 70% peak load, tests the damping under faulted condition using the test specimen of comparative example 2.
Embodiment 5 after applying 30% peak load, tests the damping under faulted condition using the test specimen of comparative example 3.
Embodiment 6 after applying 70% peak load, tests the damping under faulted condition using the test specimen of comparative example 3.
In order to observe apply damage after test effect, selected frequency and damping ratio and their standard deviation here,
The results are shown in Table 1.
The test of table 1 gained frequency and damping
Test result shows that test method test result provided by the invention is accurate, precision is higher, is that one kind is excellent again
Growing concrete test method.
Claims (9)
1. the test method damped after a kind of Damage for Brittle Material, which comprises the following steps:
(1) casting concrete test specimen, standard curing 28 days；
(2) bottom of concrete sample obtained is vertically fixed in test device, guard box is installed on concrete sample
Body simultaneously applies xial feed；
(3) protection cabinet is unloaded, applies exciting force in the upper end of concrete sample and by the way that adding on concrete sample is arranged in
Velocity sensor records acceleration signal, carries out test analysis to the power performance of concrete sample, calculates damping ratio.
2. the test method damped after a kind of Damage for Brittle Material according to claim 1, which is characterized in that described mixed
Solidifying soil test specimen is cuboid, having a size of 100mm × 150mm × 1300mm.
3. the test method damped after a kind of Damage for Brittle Material according to claim 1, which is characterized in that the survey
Trial assembly is set to universal testing machine, and the lower part of the universal testing machine is equipped with the stationary fixture for gripping concrete sample.
4. the test method damped after a kind of Damage for Brittle Material according to claim 3, which is characterized in that described mixed
The clamping length of solidifying soil test specimen bottom is 200mm.
5. the test method damped after a kind of Damage for Brittle Material according to claim 1, which is characterized in that described mixed
The upper end of solidifying soil test specimen applies exciting force, and exciting force applying mode is tapped using power hammer, and number of taps is not less than 6 times.
6. the test method damped after a kind of Damage for Brittle Material according to claim 5, which is characterized in that described mixed
The load(ing) point of the upper end exciting force of solidifying soil test specimen is on concrete sample long side center line at the position 50mm of end.
7. the test method damped after a kind of Damage for Brittle Material according to claim 1, which is characterized in that described to add
The opposite face of concrete sample exciting force acting surface is arranged in velocity sensor, is located at distance on concrete sample long side center line
At the position 150mm of its end.
8. the test method damped after a kind of Damage for Brittle Material according to claim 1, which is characterized in that the guarantor
The size of protecting box body is 100mm × 150mm × 1000mm, is formed by two L-type component combinations.
9. the test method damped after a kind of Damage for Brittle Material according to claim 1, which is characterized in that concrete
The damping ratio of test specimen, which calculates, uses following formula:
E=1200 ρ f0i/Ci 2 (1)
η=Δ f0i/f0i (2)
In formula: ρ --- the line density of concrete sample, kg/m3；
Δf0i--- the half-power bandwidth of concrete sample the i-th rank mode, Hz；
I --- resonance order: 1,2,3 ... ...；
Ci--- the i-th rank mode shape coefficients；
The elasticity modulus of E --- concrete sample；
η --- damping ratio.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110057695A (en) * | 2019-04-15 | 2019-07-26 | 北京工业大学 | A kind of apparatus and method measuring beams of concrete damping ratio |
| CN111812409A (en) * | 2020-06-05 | 2020-10-23 | 同济大学 | Online estimation method of ESR (equivalent series resistance) of direct current capacitor |
| CN113496052A (en) * | 2020-04-07 | 2021-10-12 | 同济大学 | Method for identifying damage of recycled aggregate concrete structure |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110057695A (en) * | 2019-04-15 | 2019-07-26 | 北京工业大学 | A kind of apparatus and method measuring beams of concrete damping ratio |
| CN110057695B (en) * | 2019-04-15 | 2022-03-15 | 北京工业大学 | Device and method for measuring damping ratio of concrete beam |
| CN113496052A (en) * | 2020-04-07 | 2021-10-12 | 同济大学 | Method for identifying damage of recycled aggregate concrete structure |
| CN111812409A (en) * | 2020-06-05 | 2020-10-23 | 同济大学 | Online estimation method of ESR (equivalent series resistance) of direct current capacitor |
| CN111812409B (en) * | 2020-06-05 | 2021-09-03 | 同济大学 | Online estimation method of ESR (equivalent series resistance) of direct current capacitor |
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